Imatinib Treated Chronic Myelogenous Leukemia Concomitant with Multiple Myeloma. Is There a Relationship?

Abstract 5005

Chronic myelogenous leukemia (CML) and multiple myeloma (MM) are hematological neoplasms with involvement of distinct hematopoietic cell lineages. The simultaneous occurrence of CML and MM is an extremely rare event. We report the case of a 46-year-old asymptomatic patient who was diagnosed with CML after an abnormal white blood cell count (90×10⁹ u/L) was found on a routine complete blood cell count. Physical examination showed only splenomegaly. At diagnosis, a monoclonal protein peak was observed on electrophoresis (0.82g/dL). Bone marrow (BM) biopsy was characterized by granulocyte hyperplasia without clonal plasmacytosis. Karyotype showed t(9;22)(q34.1;q11.2) and a BCR/ABL mRNA transcript was detected by RT-PCR. Cytoreduction was initiated with hydroxyurea for 20 days until imatinib 400 mg/day was initiated. Patient achieved a major molecular response (MMR) after 7 months of treatment and remains in MMR. After 12 months from diagnosis, the patient persisted with monoclonal peak, and a new BM biopsy showed 15% monoclonal plasma cells, compatible with IgG lambda Myeloma. No end-organ damage was found, and there was no indication for therapy. Karyotype was 46, XX and a FISH analysis was positive for IgH rearrangement and for del 13q. At the time of this report the patient persists in MMR for CML with a monoclonal peak of 1.2 g/dL. No evidence of MM progression has been observed. These findings indicate coexistence of CML in chronic phase and monoclonal gamopathy of uncertain significance (MGUS), progressing to smoldering MM IgG lambda during IM treatment. At this moment, the association of CML and MM has been considered coincidental, but it is possible that imatinib may induce changes in phenotype of plasma cells which might lead to progression of multiple myeloma.